1. Field of the Invention
The invention relates generally to vacuum separators having vacuum filter discs adapted for rotation through a slurry for effecting separation of solid materials, such as iron ore, from the slurry. More particularly, the invention relates to vacuum filter segments which are connected together to make up a vacuum filter disc, and which are adapted to support a filter medium and to be connected to a vacuum source.
2. Description of the Prior Art
Prior art vacuum separators have utilized vacuum filter segments which have been composed of various materials and which have been constructed as one-piece units adapted to support a filter medium. Such filter segments have included a throat which sealingly engages a vacuum manifold and communicates with a central open area which extends between the sector-shaped sidewalls of the filter segment. The sidewalls include apertures for affording communication between the central open area and the filter medium.
During operation of a vacuum separator, a vacuum is transmitted to the central open area and pulls the liquid portion of the slurry inwardly through the filter medium. The solid material or iron ore in the slurry is retained by the filter medium for subsequent removal which is effected after the filter segment has passed through the slurry by transmitting a high positive pressure or blast of air from the central open area through the apertures to the filter medium. The sidewalls of prior art filter segments have tended to wear relatively quickly, (e.g. in about one year) due to the vacuum related stresses on the sidewalls and due to abrasive wear and corrosion resulting from exposure to the slurry.
Some prior art filter segments have utilized steel sector plates which have been tack welded along the perimeter of a generally sector-shaped steel frame. The steel sector plates correspond to and wear like the sidewalls of a one-piece filter segment, and thus, the entire filter segment must often be replaced. In some situations, however, dependent on the severity of the wear, the steel sector plates can be removed from the frame and refurbished or replaced. The removal and replacement process is a troublesome and expensive maintenance operation, it requires torching or burning off the tack welds holding the worn steel sector plates to the steel frame, grinding or smoothing the resulting rough surfaces of the frame, and re-welding the refurbished or replacement steel sector plates back on the frame.
In addition to the removal and replacement of the sector plates being an expensive, time-consuming task, the torch removal of the tack welds can often result in irrepairable damage to the sector plates and/or to the sector frame, with the end result that the entire filter segment must still be discarded. Furthermore, even if the sector plates can be removed and replaced, the steel sector-shaped frame is itself susceptible to abrasive wear and corrosion. Thus, at some point in time, replacement of the steel sector plates is no longer feasible, and the entire filter segment must be discarded and replaced.
This invention is concerned with this general area and has among its objects to provide a vacuum filter segment which eliminates some or all of the above noted disadvantages of the prior art.
More specifically, the invention has among its objects to provide a vacuum filter segment which includes a generally sector-shaped frame, filter medium support means or replaceable sector plates, and fastening means adapted for removably securing the sector plates to the segment frame, which fastening means affords relatively quick and inexpensive replacement of the sector plates without incurring damage to the segment frame.
Further, the invention has among its objects to provide such a filter segment wherein the fastening means are adapted to afford removably securing different types of sector plates to the segment frame.
Further, the invention has among its objects to provide such a filter segment wherein the segment frame and sector plates are highly resistant to abrasive wear and corrosion.